1. Field of the Invention
The invention pertains to the field of collapsible tubes and more particularly to caps for such tubes. The invention is particularly useful for collapsible tubes of the type used for eye medications having an eye tip, the tubes having therein a form of tamper evident means that disclose any prior opening of the tube.
2. Description of the Related Art
The Art
In U.S. Pat. No. 3,731,849 issued May 8, 1973, for Container and Cap Combination To Indicate Tampering, there is shown a collapsible tube of the type having a collapsible body and a rigid shoulder which terminates in a tapered nozzle having an orifice in the end. The nozzle has on the outside thereof in the area of the shoulder a threaded boss which receives thereon a cap. The cap has a tapered hollow post which generally conforms to the tapered nozzle. Such cap design is necessary for efficient closure of the orifice when the cap is screwed on the tube. Such collapsible tube design is particularly used for eye medications wherein the nozzle having an orifice at the end thereof permits the medicine to be accurately deposited in the eye.
To show tampering with the contents of the tube, the '849 patent discloses an arrangement wherein a flange is formed on the tube above the tube shoulder, and a flexible skirt formed integrally on the cap is initially positioned under the flange. When the cap is initially unscrewed from the tube, the skirt flexes under the rotational and longitudinal forces imparted to the cap and escapes from beneath the flange. Any effort to rescrew the cap and reposition the skirt below the flange is thwarted by the outward flair of the skirt. Upon rescrewing it is then evident that the cap has previously been initially removed, since it must rest above the flange. The arrangement described above as disclosed in the '849 patent works well to indicate tampering.
The Problem
Except when there has been tampering, the user must be the one to initially remove the cap when the skirt is beneath the flange. The user must exert a substantial rotational force to initially unscrew the cap and flex or deform the skirt from beneath the flange, since the skirt resists such flexing or deformation. It is difficult for the user with the prior art cap, to exert such substantial force.
The difficulties occur because of the prior art cap design. The relatively short base of the cap is difficult to grasp with the fingers for rotation, since it is relatively short. The user also attempts to grasp the post of the cap, which is tapered and smooth and which conforms to the nozzle of the tube. This post design encourages the fingers to slide away from the base and away from the cap. In effect, the harder a person tries to grasp the base with the fingers, to initially unscrew the cap, the more the fingers want to slide away from the base of the cap. Even the ridges on the base help little. This makes it extremely difficult to initially unscrew the cap and flex or deform the flexible skirt thereon from underneath the flange.